Preparation:

Step 1: Preheat your oven to 375°F (190°C).

Step 2: Cook the cheese tortellini according to the package instructions. Once done, drain and set the tortellini aside.

Step 3: In a large skillet, heat 1 tablespoon of olive oil over medium heat. Add the diced onion and sauté until soft and translucent, about 3-4 minutes.

Step 4: Add the minced garlic to the skillet and sauté for another minute until fragrant.

Step 5: Introduce the ground beef to the skillet. Break it up with a spatula and season with salt, pepper, and Italian seasoning. Cook until the beef is browned, about 6-7 minutes. Drain any excess fat from the skillet.

Step 6: Stir in the marinara sauce with the beef mixture and let it simmer for 5 minutes to meld the flavors together.

Step 7: In a large baking dish, combine the cooked tortellini with the beef and marinara sauce mixture. Mix everything together evenly.

Step 8: Sprinkle the top of the dish with shredded mozzarella cheese and grated Parmesan cheese.

Step 9: Place the baking dish in the preheated oven and bake for 15-20 minutes, or until the cheese is melted, bubbly, and golden brown.

Step 10: Once baked, remove from the oven and garnish with fresh basil leaves before serving.